<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
            // number,string,boolean,undefined,null
            var num=10;  //数值型
            var str="hello world";  //字符串
            var b=true;//boolean类型只有两种:true false
            // typeof 操作符去判断  查看类型
            console.log(typeof num)
            console.log(typeof str)
            console.log(typeof b)
    </script>
</body>
</html>